Explicit Web Proxy Enabled Facing Internet

Hi,

I have FortiGate 1000D running 5.4.3 firmware version which is subject to be a publishing firewall.

Objective:

Migrate all publishing policies from ISA instance Firewall (windows VM) to FG1000D.

Problem:

There's a lot of duplicate IP's which are not possible to migrate through VIP.

Example:

Public IP: 1.1.1.1 mapped to Private IP: 2.2.2.2, Port: 80, url: test.example.com

Public IP: 1.1.1.1 mapped to Private IP: 22.2.3, Port: 80, url: test1.example.com

Solution:

The solution I have seen is enabling explicit web proxy in the interface connected to the Internet then use headers to mapped it since it say's duplicate when using VIP. The problem is I don't know if this work or possible and how to do it. Did someone already configure something like this? Or do you have procedure or other way to resolved the issue in duplicate error when using VIP? Thanks

Regards,

Marlon